1. Technical Field
The present invention relates to an image display system, an information processing apparatus used in the image display system, an image display apparatus used in the image display system, an image correction program used in the information processing apparatus, and an image correction program used in the image display apparatus.
2. Related Art
There is known an image display system including a personal computer (hereinafter, referred to as ‘PC’), which serves as an information processing apparatus that supplies image data to be displayed, and a projector that projects an image image-processed by the PC on a screen.
In such image display system, various kinds of correction processing are performed for image data transmitted from the PC to the projector using an image processing unit in the projector. In addition, the various kinds of correction processing include resolution conversion, edge enhancement, black and white expansion, shape correction, color conversion, gamma correction, VT-gamma correction, ghost correction, crosstalk correction, and color unevenness correction, for example.
For this reason, the image processing unit in the projector becomes large, which is one of the causes of cost increase. Moreover, in order to realize an image with higher quality, highly precise processing is needed. Accordingly, it is necessary to mount a high-performance image processing unit, which further increases the cost.
In order to cope with such a problem, there has been proposed an image display system in which the various kinds of correction processing described above are performed in a PC and image data after correction processing is transmitted to a projector through a signal transmission unit, such as a USB cable (for example, refer to JP-A-2004-69996 and JP-A-2004-88194).
In the image display system described above, most of the image processing is performed in the PC, and accordingly, it may be possible to make the configuration of a projector very simple. In addition, since the PC originally has a graphic processing function, such as a GPU (graphic processor unit), highly precise image correction may be performed without adding a new function in the PC.
Each of the image display systems disclosed in JP-A-2004-69996 and JP-A-2004-88194 has the configuration in which a PC and a projector are connected to each other through a USB cable. For this reason, it is difficult to transmit a high-definition image based on, for example, Hi-Vision standard with a transmission rate of 60 frames/sec. Therefore, it is general that a PC performs compression processing for image data after correction processing and then transmits the compressed image data to a projector. Particularly in the case when the image data is a motion picture, it is common to transmit differential data of a portion that changes for every frame.
In the case when all kinds of correction processing are performed in the PC, image data is corrected with high definition; however, since the correction processing is performed on most pixels of the image data, variations in most pixels occur in previous-frame image data and present-frame image data even if differential data between previous image data and present image data is applied.
Thus, since a data compression rate becomes low even if the differential data is applied, the amount of data transmitted from the PC to the projector significantly increases. As a result, a problem occurs in which the deadline of data transmission from the PC to the projector is not met and a frame rate for image display in the projector is not appropriately maintained.
In this case, for example, it may be considered to suppress the degree of image correction low such that the differential data does not become too large. However, this is not a proper method because the quality of a display image deteriorates. Alternatively, the differential data may be made small by making rough differential data such that a small change between image frames is not detected when obtaining the differential data. However, since present image data reproduced by the projector is deficient in information, the quality of a display image deteriorates. Accordingly, this is not a proper method either.